Income taxes - Current Income Tax Expense (Recovery)/ Deferred Income Tax Expense (Recovery) by Jurisdiction (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current income tax expense (recovery):
Current income tax expense (recovery)	$ (710)	$ 1,230	$ 880
Deferred income tax expense (recovery):
Deferred income tax expense (recovery)	(923)	10	288
Income tax expense (recovery) from continuing operations	(1,633)	1,240	1,168
Canada [Member]
Current income tax expense (recovery):
Federal	(404)	699	454
Provincial	(304)	530	319
Deferred income tax expense (recovery):
Federal	(526)	6	169
Provincial	(397)	4	119
Other [Member]
Current income tax expense (recovery):
Other	$ (2)	$ 1	$ 107